


Cat Scratch Fever

by TookMeASecond



Category: Supernatural
Genre: Alpha Sam, Alpha/Beta/Omega Dynamics, Bottom Dean, Creature Fic, Creature Fic Tile, M/M, Omega Dean, SPN A/B/O Bingo, Top Sam, Werecats, i have no idea what i did
Language: English
Status: Completed
Published: 2018-06-29
Updated: 2018-06-29
Packaged: 2019-05-30 11:05:52
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 9,624
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15095411
Author URL: https://archiveofourown.org/users/TookMeASecond/pseuds/TookMeASecond
Summary: Prompt:On a routine hunt gone wrong, Sam gets bitten / gets some kind of serum injected that turns him into a werecat. He develops all sorts of catlike tendencies and full on transforms into a giant cat on the next full moon. He's not rabid during that time, but not harmless and friendly either. Now he and Dean have to find a cure and also deal with the feelings Sam just can't hide anymore, because of his stronger instincts.(full prompt in end notes)





	Cat Scratch Fever

**Author's Note:**

> I feel like I failed on this one, it turns out I didn't follow the prompt completely and I debated heavily on whether or not I was going to post.

Sam was in trouble.  Not that that was anything too new, they often found themselves getting by by the skin of their teeth.  Or something’s teeth. At this point in time said teeth were about two inches from his face, the teeths owner ready to rip it off.  The Alpha struggled to push the half-human half-what-the-fuck-ever, off of him before it sank those gnarly yellowed teeth into his cheek, but he was slowly losing inch by inch.

 

In a last ditch attempt at getting the upper hand Sam let go with his right, the creature’s sharp canines rushed forward just as his arm slammed down on the things shoulder, causing it to lose traction and slip.  Sam threw his head back and yelled at the pain that burst in his left pec. The thing on top of him still managed to get a good bite, just not anywhere lethal. Not yet at least.

 

“Sam!”  He heard his brother yell from somewhere across the room.  He was fighting his own shifter, Sam just had to hold on a little bit longer.  He grabbed the thing by the scruff of its neck, trying to keep it from shaking its head and ripping the flesh from his chest; but also not wanting to yank it off lest the same thing happen.  The shifter growled low in its throat and its jaw loosened a bit, it might have even arched its back and pressed a bit into Sam’s hand.

 

Weird.  But good enough.

 

Sam used his moment of distraction to slam his left fist into the things face, there was some tearing on his chest but mostly the thing let go and went sprawling next to him.  Sam dove for his silver knife, that had been just out of reach, and by the time he turned to finish the job the were-something was diving for him again. It met him in the middle, the creature’s momentum carrying it onto the blade.  He saw the shock when contact was made, felt the warm ooze of blood as he twisted the knife just so. He snarled at the thing as he felt it go limp and sink to the floor.

 

“Sammy!”  Dean was closer now, probably coming down the hallway.

 

“Yeah!  Dean, I’m good,” he called out falling backward onto the old wooden slats of the floorboards.  Why did these things always live in decrepit houses? Sam closed his eyes and tried to catch his breath.  The skin around his bite wound burned and he reached up a lazy hand to press against it, wincing at the sting.

 

“Shit, man.  Give a guy a heart-”  Dean’s voice trailed off when his eyes fell on the red soaking through Sam’s shirt.  His eyes went wide and he looked between the wound and Sam’s face. Sam shook his head and moved his hand as Dean kneeled at his side to get a better look.

 

“I’m good, man.  It’s just a scratch.”  Dean gave him a skeptical look as he peeled the torn flannel from his brother’s chest.  His omega instincts to take care of his family overriding anything else. He poked and prodded the wound gently.

 

“Alright, it’s not too deep.  Can you walk? We should get out of here and clean this up.”  Sam smiled indulgently and rolled his eyes when his brother wasn’t looking.  He let Dean help him to stand and they gathered their tools and left the house with accelerant and a lit match.

 

~*~

 

A measly two days after Sam got bit the wound was mostly healed; Dean chalked it up to his superior first aid skills and Sam’s good Alpha genes.  The edges of the teeth marks were a silvery-red, the middle of the punctures still looking a bit raw. Sam had been fine twenty-four hours after the bit.  Dean was convinced after forty-eight he wouldn’t be infected by anything. Shifters didn’t work like that right? Right.

 

Besides, those things weren’t werewolves; that he was sure about.  Some kind of shifter creature. Silver worked just fine and their bites didn’t turn their victims.  Sam let Dean fuss over him for a while; cleaning the wound, making him food, having him rest up on the couch and be completely lazy.  Dean may brag about being the Alpha-iest omega, but he was still solid omega.

 

Dean was in the kitchen of the bunker, cooking some chicken on the stove (he really needed to invest in a grill), when Sam came through the door with his nose in the air.

 

“What is that?  That smells amazing!”  Dean looked over his shoulder at his brother, eyebrows raised and looked Sam up and down.

 

“Uh, thanks.  I guess. Just chicken man.  Don’t worry, I’ll put yours over a bed of rabbit food.”  Dean poked at the chicken again, testing it’s give. He had it in his favorite cast iron grill pan, so at least the chicken appeared grilled.  Sam appeared over his shoulder, inhaling quick little bursts through his nose, his mouth slightly open. Dean leaned to the right and looked at him confusedly.

 

“Dude!  Have a seat or something, crowding me wont make it cook faster.”  Sam gave one last sniff and exhaled deeply with a groan. He looked pained to move away from the stove, but did as he was told.  Dean shook his head and grabbed a couple plates from the cabinet. He got Sam’s salad mix out of the fridge and hefted a good portion to the middle of the plate.  His own got sauteed mushrooms and onions with mashed potatoes.

 

Once the chicken was done he diced up Sam’s breast and brought the plates to the table.  Sam nearly yanked his chicken from Dean’s hand and didn’t bother getting a fork. He started picking up the pieces with his fingers and nearly shoveling them into his mouth.  Dean chewed his first bite slowly as he watched Sam devour the meat on his plate.

 

Sam looked up with a mouthful and froze at the look on the omega’s face.  They sat for a minute, locked in confused stares, before Sam swallowed what he was chewing and took a drink of his water.

 

“Thanks, Dean.  This is really good.”  He grabbed his napkin and wiped his face, trying to look nonchalant about picking up another piece and putting it in his mouth, chewing slowly.

 

“Uh, huh.”  Dean nodded, still looking curiously at his brother.  They finished the meal in silence and with less gusto, though Dean had to admit he was a damn good cook.

 

“That was great, is there any more chicken?”  Sam craned his neck up to scour the counter, looking for more of the food.  Dean eyed the plate in front of the Alpha and cocked an eyebrow at the salad left untouched, except for Sam to move lettuce to find more meat.

 

“Sorry, man.  That was it. You don’t want your salad tonight?”   One corner of Sam’s mouth rose and fell quickly as he stood from the table, leaving his plate, and went to the refrigerator.

 

“No, not feeling it tonight,” he said as he moved things around.  He made a happy little noise of triumph, Dean smiling despite himself, and closed the door.  A small baggie of pepperoni slices in one hand and a bottle of water in the other. “I’m gonna be in the library.  I’m sure there’s a case we could be getting to. Just need a snack.” Sam left in a hurry, seemingly pleased about his find.  Dean shook his head and smirked.

 

“Kids after me for years to eat more greens.  Doesn’t eat his greens. Don’t be comin’ at me with that shit if you’re not going to eat em yourself,” Dean mumbled half heartedly to himself.  Then he looked back up at the doorway before sneaking his fork across the table and stabbing at some lettuce. He poked a piece of his chicken with it and took the bite.  His upper lip curled in distaste and he chewed like the food offended him before shoving Sam’s plate away and finishing his own dinner.

 

~*~

 

Okay, Sam was acting weird.  It wasn’t too obvious. Any of the things Sam was doing would be fine on their own.  It was an accumulation of weird behavior. Like the salad thing. Sam loved salad, and he had been refusing to eat anything that wasn’t meat for three days now.  Then there was the touching. He always seemed to need to be near Dean if they were in the same room. Instead of sitting across the table he’d sit right next to Dean.  On the couch they were practically plastered together, sometimes Sam had a hand on Dean’s leg.

 

Maybe he was getting close to rut?  It was possible, Dean couldn’t remember exactly when Sam’s last rut took place, he didn’t keep track of such things.  He should probably ask. Usually when Sam was close he’d start preparing his room and getting ready to lock himself in.

 

Dean was searching for his brother everywhere.  He wasn’t in the bunker, by now that was for sure.  The last place he hadn’t checked was the garage, but Sam didn’t usually hang out in there at all.  When he stepped into the open space he noticed the bay door to the outside was open. Huh. Maybe Sam went for a run and didn’t tell him.

 

As the omega got closer to the opening he saw a pile of clothing on the floor off to one side of the door.  What the fuck? Was Sam streaking now? He bent to pick up the shirt on the top of the pile and was struck with a wave of Sam’s pheromones.  Okay, rut was definitely coming. He sniffed the shirt tentatively, it smelled like Sam for sure; just sharper and stronger than ever.

 

Dean looked out the door and scanned the open field around the bunker.  His shoulders sagged when he saw his brother sprawled out on a rock to the left of the garage entrance.  He was naked, of course, on his stomach in the sun. His eyes danced over the planes of Sam’s flesh, his muscles looked cut from stone.

 

The omega blamed it on Sam’s rut pheromones and the fact that he hadn’t been laid in a while when Sam arched and stretched, rolling onto his back in a very lazy manner.  He was half hard in his sleep on the sun-warmed stone, the bulge of his knot obvious at the base. Dean couldn’t tear his eyes off his brothers muscled form.

 

He had no idea how long he stood there and entertained odd thoughts about his own kin when Sam slowly moved to sit up and run a hand back through his hair.  Dean dodged back behind the garage wall and dropped the shirt that had somehow made it to his nose.  _ Shit _ .  What the fuck was that?  Before the young Alpha had a chance to catch him Dean made a mad dash to back to the main part of the bunker and into the shower.

 

Fine.  Maybe they were both being weird.

 

~*~

 

A week after Sam and Dean got back from the last hunt Dean was starting to get a bit restless.  Sam continued his odd behavior and his scent kept getting stronger and more musky. He was beginning to wonder why the rut was taking so long, and why Sam hadn’t mentioned anything.  At least he hadn't been looking for cases, that was a sign he intended to stay at the bunker. Which was safer when one of them was in rut or heat.

 

Dean was coming back from the shower, a towel around his waist and one scrubbing over his hair, when he noticed something on the floor in front of his door.  He stopped and looked around the hall before advancing on his door. Before he even got to it he knew it was his favorite Zeppelin vinyl. His brows furrowed together as he inspected the sleeve.

 

“Huh.”  He looked down the hall again, half expecting Sam to jump out and yell surprise or something stupid.  Why would he put Dean’s record at his door? He’d been keeping his growing collection in the library, had taken over one of the book shelves for his player and everything.  He went into his room, putting the record on his bed before getting dressed. There had to be a reasonable explanation.

 

“Heya, Sammy.”  Dean said plopping the vinyl on the table next to his brother.  Sam looked down at it then up through his lashes at Dean. “Wanna tell me what this is about?  Why was it on the floor?” Sam sat up straighter and put his fingertips on the sleeve. Dean narrowed his eyes a bit and tilted his head to the side.

 

“I thought you’d like it.  It’s your favorite.” Sam’s own eyebrows went up as if he were confused about what Dean was really asking.

 

“Yeah, and?”  Sam looked down at the record and moved to put the flat of his hand over it.

 

“I don’t know.  I thought you’d like it.  Just wanted to make you smile or something.  I don’t know.” Sam removed his hand and went back to his book, looking a little put out by Dean’s reaction.  The omega stood and stared at his brother for a while, Sam gave no indication he was bothered one bit.

 

“Right.  Uh, Sammy, how long until your next rut?”  That got the Alpha’s attention. He looked up, slightly confused, and frowned, thinking.

 

“Uh, well.  Not for a month or so.  Why?”

 

“You sure it’s not going to be sooner?  Cause you’ve been acting a little weird.  And you smell… more.” Sam’s eyebrows shot up at that and he leaned back in his chair, slightly amused.

 

“I  _ smell  _ more?  Like what, Dean?”  His cheshire cat grin looked way too smug for someone who had just gifted Dean with his own vinyl.

 

“I don’t know.  More. Stronger.  Like, more musky.”  Dean shifted on his feet, slightly uncomfortable.  He’d been trying  _ not  _ to pay too much attention to how Sam smelled lately.  And he’d never considered how to describe it to the Alpha himself.

 

“ _ Musky _ ?”  Sam asked leaning forward with a huge smile on his face.  “You think I smell musky?” Dean rolled his eyes and turned around, hiding himself from his brother.

 

“Whatever, Sam.  You’ve been acting weird, and I don’t track your cycle, and I was just curious is all.  Maybe it’s the full moon coming up. People get weird on the full moon.” Sam laughed behind him and Dean grinned despite himself.

 

“Yeah.  The full moon.  That has to be it.  You been reading your horoscope again?”

 

“Shut up, bitch!”  Dean moved to the other side of the table and plopped into a chair, grabbing a random book from in front of Sam and opening it to a random page.  “What are we reading about anyway?” Sam sat back and rested his chin on his thumb with his pointer finger over his mouth for a moment before answering.

 

“Dynamics of shifter packs and mating habits of Alpha shifters.”  Dean made a disgusted sound and close the book, shoving it toward Sam and dropping his forehead to the table.  The library was quiet for a moment before he heard something sliding across the table. It was just a second before it stopped.  Then there was a pause and the sound was back for another second. This happened a few times before Dean’s head shot up.

 

“What the hell are you doing now?” he accused his brother with a bitch-face to match his irritated tone.  Sam just shrugged and shook his head, but Dean noticed the vinyl sleeve nearly halfway off the table. He narrowed his eyes at it, then at Sam.  “Don’t you dare.” The words were nearly a growl.

 

Sam smirked and deliberately put the tip of his pointer finger on the sleeve, pressing down and tipping it off the table to hit the floor with a splat.  Dean’s mouth hung slack, he looked incredulously from the edge of the table to Sam’s more than amused face.

 

“Are you fucking serious?”  Dean sounded dangerously calm, Sam smirked behind his hand, completely unperturbed about his brother’s seemingly docile anger.  “You’re fucking dead!” The omega dove over the table to grab his Alpha, but Sam was ready for it. He sprung from his chair and careened down the hallway, laughing the entire time.

 

~*~

 

Sam may have insisted his rut wasn’t due yet, but Dean still insisted on some down time.  Just in case. Besides, they’d earned it right? That last hunt was a little rough. Sam was lucky that bite didn’t get infected or turn him.  And, if he needed anymore motivation, it was the full moon and he had a horror movie marathon to watch.

 

“I just don’t see the appeal.  Our lives are basically a horror movie.  Why would you want to watch them on TV?” Sam asked as he watched Dean gather his snacks in the kitchen.  Popcorn, beer, nachos, pretzels with beer cheese, napkins.

 

“C’mon, Sammy!  We can watch together.  I usually make fun of them in my head, but you can chip in with me, it’ll be hilarious!”  Sam rolled his eyes but got up from the table to help Dean carry his stuff into the living room anyway.  And since he was already there he might as well sit down and keep his brother company. It wasn’t even dark out yet, and he had nothing better to do.

 

An hour and three beers into Rob Zombie’s Halloween Dean had to pee.  He got up without bothering to pause, he’d seen it countless times before.  Sam was zoned out and waved him off with a grunt. Dean took a leak and decided to stop by the kitchen for more snacks.  Beef jerky, an entire pie, a tub of pistachios (for Sam).

 

When he got back to the living room the movie was still going, but Sam was gone.  Dean rounded the couch and plopped back onto his spot, depositing the bin of nuts to where Sam was sitting.  Right on top of Sam’s clothing.

 

“What?  Again?” Dean gripped to himself looking around.  Where the fuck did he go now? And why did he go there naked?  Dean grabbed at the pile of clothing and started shaking it out to fold up when he noticed it was ripped in a few places.  Not really shredded, but definitely looked like it had been torn from Sam’s body.

 

Movie forgotten he was suddenly on alert.  He wanted to turn the volume on the TV down or off but didn’t want to give himself away.  He strained his ears, concentrating on anything not in this room. He looked again at the clothing he’d tossed back on the couch.  There was no blood, not even a drop. He leaned forward to set his beer on the coffee table and stood in one fluid motion.

 

Nothing in the room was displaced, there was no sign of struggle.  Then he heard it, something like soft swishing. It was rhythmic and slow.  He strained his ears to try and figure out which direction it was coming from, which hallway he needed to be facing.  Then something bumped the back of his thigh, just under his ass cheek and he nearly jumped out of his skin spinning and leaping out of the way to face the…

 

“Holy fucking shit!” he yelled as he jumped back again and held his hands, palms out, in front of him.  He crouched slightly, trying to look smaller and unimposing to the giant creature staring calmly at him.  “What the fuck?” he whispered to himself.

 

A fucking huge ass cat… lion?  Tiger? It looked dark sandy, like a lion, but had a frill instead of a mane, going from the middle of its forehead all the way down to between its shoulder blades.  There were darker brown stripes that started at the tops of his ribs and went down to curl under its belly. It was Alpha.

 

“Easy there, buddy.  How the hell did you get here, uh?”  Dean’s heart was jackrabbit quick in his chest, he was inching backward with his hands still up, his mind racing to assess the situation.  It wasn’t attacking him. It had touched him, bumped into him when he wasn’t even looking. It must have been the soft sound he heard, so this thing was stealthy.  And fucking huge!

 

The big cat licked his lips slowly, his hazel eyes looked slightly bored as he took in the sight of the omega behind the couch.  Dean debated on whether he had time to get to a weapon. There were plenty stashed around the room, but he didn’t even know what this thing was and if he grabbed the wrong one and pissed it off he might not make it long enough to go for another.

 

“Gods, where the fuck is-” he started wondering about Sam.  His eyes darted to where the pile of clothing sat on the couch.  Torn but not bloody. Sam’s odd behavior recently. Sunning himself, knocking things off the table, his aversion to vegetables.  “What the fuck?”

 

If this was Sam, if somehow Sam had turned into the lion-tiger-thing why was he so calm?  Why wasn’t he freaking out? Dean decided to go for broke. What the hell right?

 

“Uh, Sammy?” he asked, his voice tentative and more shaky than he’d ever admit to.  The cat, who had been scanning the room calmly, snapped his eyes to Dean’s. Yup. He knew those eyes.  This was his fucking brother. Sam was a Gods damned cat! Oh, shit. Oh for the love of fuck. The bite.  They should have known they weren’t going to get out of this unscathed.

 

The cat seemed docile, so Dean relaxed his defensive position a bit and tried to take a few calming breaths.  Cat-Sam seemed to take this as an invitation to get closer. He padded over on huge, silent feet and bumped his forehead into Dean’s thigh again, squinting his eyes closed and rubbing his cheek over the rough denim of Dean’s jeans.

 

“Alright, little brother, we’ll figure this out, okay?  We’ll get you back to normal. Or at least as normal as our lives are.  It’s kinda fucked up that this isn’t the weirdest thing that’s ever happened to us.  I mean, it’s pretty out there, definitely in the top ten, but-” Dean cut his rambling short when Sam wrapped a huge paw around his calf, digging in lightly with his claws and nipped at the sensitive flesh of his inner thigh with his sharp canines.

 

“Ow!  Bitch!” Dean yelled trying to jump back, but Sam had a good hold of his leg and was rubbing his cheek over the sore spot he’d just made.  Dean hopped around on one leg for a second before Sam released him and looked up into his face. The omega could swear the fucker was laughing.

 

“Come on, let’s take this to the library.  Research, yay,” Dean cheered sarcastically as he turned on his heel to walk down the hallway.  He was fully expecting Cat-Sam to follow. He was not expecting a clawed paw to hook his ankle, digging in slightly, and tug.  Dean went sprawling across the floor, lucky to catch himself on his hands. He grunted in surprise before trying to push himself up.

 

“What the fuck, Sam?” he yelled turning his head to look over his shoulder.  Then there was a solid weight on his back, two giant paws on either side of his head.  Cat-Sam slowly pressed his belly into Dean’s back, pinning him to the floor effortlessly.  Jeeze, this cat was fucking heavy. Dean panted a few times, racking his brain for a solution to his sudden problem.

 

Then Sam’s claws started to flex against the floor, actually digging in and leaving marks in the linoleum.  He alternated between his left and his right, scratching deeper each time. Then Dean felt a warm, wet,  _ scratchy  _ sensation on the back of his neck.  Cat-Sam was fucking licking him!

 

“Sam!  Dammit, get the hell off me!  Stop! Ow!” The tongue of a cat was rough, covered in little hooks that aided them in cleaning dirt from their fur, or flesh from bone.  It rubbed his skin raw in only a few swipes, but Sam didn’t stop. Dean took as deep a breath as he could get and tried to push up with his arms and shove the cat off.

 

With cat-like reflexes (huh) Cat-Sam growled in his throat, a menacing sound, and sharp fangs closed over the back of Dean’s neck.  The omega froze on instinct, stopped pushing up and darted his eyes around frantically. This wasn’t good. So not fucking good. He was no match for the strength of the cat, and Sam didn’t seem to be in charge right now.

 

Dean’s mind raced on what he was supposed to do.  What if Cat-Sam didn’t let go? All he had to do was squeeze his jaws and he could snap Dean’s neck like a twig.  Dean never really minded being omega, he’d worked hard to be strong enough to defend himself. Never in his life had he felt as helpless as he did in that moment.  The fact that it was Sam on his back made it worse.

 

They were both frozen, as if each was waiting for the other to make a move.  Dean had no moves left. The sudden thought that if he got out of this he might have to kill his brother before they got him back to normal had tears stinging his eyes.  Could he do it? He’d always said he’d rather die than let anything hurt Sam. Could he hurt him in self defense?

 

Suddenly Cat-Sam let go and moved off of him, sauntering down the hallway with the tip of his tail twitching side to side.  Dean let out a breath against the linoleum, afraid to get up at first. He wasn’t quite sure yet what was going to set Cat-Sam off.  He looked back up and watched the creature sniff the air, then mosey into the library as if he didn’t just have Dean’s life in his jaws.

 

As soon as the tail slipped past the doorway Dean pushed himself to his feet.  He was about to go find something that would be able subdue the creature if he needed to when Cat-Sam poked his head out of the library door and opened his mouth.  Dean expected some deep roar, or maybe a loud hiss.

 

Cat-Sam fucking  _ chirped _ .

 

Dean narrowed his eyes a little and looked at the creature, extremely confused.  Such a small sound coming from such a big animal was just strange. Cat-Sam chirped again, just a quick push of his chest had the sound travelling down the hallway.  Dean shook his head and took a couple steps forward. Cat-Sam started to pur.

 

“Holy shit, Sammy.  When this is all over I am giving you such shit over your behavior.  You’re never going to hear the end of it, man.” By the time Dean made it to the doorway Cat-Sam was full on motor boat purring at him.  His tail twitching back and forth, his hazel eyes had a black slit in the middle where his pupils were contracted. When Dean tried to walk past he got a head but to the side of his leg, and he could actually  _ feel  _ the vibrations coming through the big cat.

 

“This is so fucking weird,” Dean grumbled to himself as he took a seat at the table.  He grabbed the closest book to him and read the title.  _ Types of Shifters _ .  Sounded like as good a place as any.  He flipped to the beginning, hoping this one had a table of contents.  Most of the handwritten ones did not. Some that were printed had the foresight to add notes like that.  No such luck.

 

He sighed as he started skimming through the first chapter.  At least those were labeled. He only had to go as far as chapter three before he came upon werecats.  Seemed legit. The things they were hunting when Sam got bit were catlike, and Sam was a cat right now.  Before he even got past the first chapter he was joined at the table, but not in a way he would expect of Sam.

 

The lion-tiger jumped up effortlessly and stalked toward Dean with his head low, tail still twitching.  When he got to the omega he headbutted him in the face, and Dean winced, squeezing his eyes shut.

 

“That’s going to get fucking old, fast,” he groaned as he rubbed his cheekbone.  Cat-Sam didn’t seem to care at all. He sniffed at Dean’s eyes for a second, then turned to, hopefully, move on down the table.  Again, no such luck. Cat-Sam turned just enough so he was sideways along the table and plopped down, rubbing his cheeks on the table top and rolling onto his back so that his legs flopped in the air.  He pressed the top of his head into the table and turned to look at Dean upside down.

 

When the omega didn’t react Cat-Sam reached out a sandy paw and nudged Dean on the chin, one of his claws catching and snagging under the skin slightly.

 

“Ow!  Come on, man!  Watch the nails,” Dean scolded and batted the paw out of the way.  He knew he couldn’t get Sam to stop if he wanted to, and he realized his mistake too late.  The game was on.

 

Cat-Sam rolled onto his side and wrapped his front paws around the book and Dean’s arm that was holding it.  His back feet came up, curled underneath him, and he kicked at the book, shredding the edges of the pages with his back claws.  His jaws came down on Dean’s forearm, biting much more gently than he had on his neck. Dean still screamed. He shoved his chair back and it fell to the floor with a clatter.

 

The lion-tiger on the table was flipped onto crouched legs in the blink of an eye, his tail slightly puffed out and his pupils large and searching.  His ears were flat on his head and he looked ready to bolt at any second. Dean froze, half standing, and watched the werecat on the table for any sign he was about to attack.

 

When Cat-Sam didn't move Dean began to ease back to pick up the chair.  As soon as he started bending down the creature on the table started scrambling, digging deep grooves into the table as he tore down the length of it.  At the end he leapt as far as he could down the steps and around the circle stairs where he crouched and peeked at Dean through the metal with his ears still pinned.

 

“What the fuck is wrong with you, Sam!” Dean yelled after him while surveying the mess.  The book he was thumbing through was torn to shreds and he hadn’t even had time to get through it.  The other books that were stacked nicely were tossed aside and to the floor. There was shredded paper everywhere.  Sam was going to be pissed at himself when Dean got him back.

 

More of the quiet swishing had Dean looking toward the door where Cat-Sam disappeared to.  The nerve of that fucking thing. He was sashaying into the room as if nothing had just happend.  Jumped back up onto the table and promptly sat on his haunches. He swished his tail from left to right in a wide arch a few times before bringing up his paw, closing his eyes and licking the side of his foot.  He wiped it down his face and repeated the process.

 

Dean looked on with wide eyes and his mouth hanging open.  “Are you fucking bipolar!” he yelled at the cat. Cat-Sam paused in his licking and opened his eyes to stare at Dean, expression unreadable.  Then just as he’d stopped he closed his eyes and started again. Dean dropped his head back and made an exasperated sound at the ceiling.

 

With the antics going on it was easy to forget how powerful Cat-Sam was.  Dean decided to leave this mess for another time and try to find something on his laptop.  At least Cat-Sam couldn’t shred that. Actually, he probably still could, but Dean could lock himself in his room.  That might work.

 

He turned on his heel to leave the library and heard the lion-tiger jump off the table and the quiet sound that meant his padded feet were walking on the linoleum.  When it stopped he turned to look over his shoulder. Shit.

 

Cat-Sam was halfway out the door, Dean could see half his head and his shoulder.  His eye was focused on Dean, a wiggle to his shoulder told Dean he was adjusting his back feet to pounce.  Then he wondered how he knew so fucking much about cats. Although, that thought immediately took a backseat to the knowledge that he was being hunted.  He stopped moving, Cat-Sam did the same.

 

Dean turned back to look at his door.  He was right between the library and his room.  He wouldn’t make it at this rate, and he had no intention of finding out what his stalker would do once he was caught in this game.  He took one step toward his room while watching Cat-Sam in his peripheral vision. His step had the creature inching out into the hallway more.  Crap. He turned to full on watch his brother as he stepped slowly toward his room again. This time Cat-Sam stayed put.

 

Okay, he could do this.  He kept his front presented to the lion-tiger and started walking backward to his door.  Cat-Sam let him get three or four steps before he calmly started to advance. His hunched form told Dean he was still being stalked.  He bailed on his plan and turned to run to his room, just making it inside the door when Cat-Sam slid by, not getting traction on the smooth floor without his claws.

 

Well, at least Dean now knew he wasn’t about to be clawed to death.

 

The door slammed behind him before Cat-Sam could make it through.  Dean didn’t bother locking it, without fingers he couldn’t turn the handle.  Besides, if his brother was going to break the door down he’d do it whether it was locked or not.  The creature started yowling in the hallway. At first he just paced in front of the door. Then he started banging and scratching at it.

 

Dean watched as the lion-tiger’s nails actually punctured the wood.  Four neat little holes the blade-like nails came through. Shit. He rushed to open the door before Sam could break it down.  He’d still have to fix it, but he still had a door. Cat-Sam strolled in as if nothing were wrong, twitching his tail and sniffing around delicately.  Dean shook his head and grabbed his laptop, plopping down on his bed.

 

“You can hang out, I guess.  But you have to let me get some work done.  I need to figure out how to fix you, Sam. And stop hunting me!  If you can agree to do that I won't have to try and lock you out.”  He looked to Cat-Sam as if he expected a response. The creature just wandered the room, his velvet looking nose twitching as he investigated Dean’s territory.

 

“If you spray in here I swear to the Gods I will end you.  Brother or not,” Dean grumbled under his breath. He wasn’t sure he could.  He knew silver killed shifters, and even if he didn’t get Sam at a vital point he could still injure him enough to slow him down.  But he’d rather cure him.

 

It wasn’t long before Cat-Sam got bored with investigating Dean’s room and joined him on the bed.  With little disregard for the laptop sitting on Dean’s stomach he headbutted the back of the screen, nearly pushing it off him and laid himself between the omega’s legs and half on his stomach.  Cat-Sam’s big paws covered the span of it, curving slightly down over his ribs.

 

“Fuck, Sam!  Come on!” Dean griped at him as he steadied and shifted his laptop.  Sam laid there with his head up and his eyes closed, chest puffed out.  His claws started to flex again, pulling at Dean’s t-shirt and digging in gently.  Dean shook his head, well aware he was helpless to stop what was going on and tried to find his spot in his reading again.

 

Cat-Sam started a deep pur in his chest, Dean could actually feel the vibrations on his dick where Sam’s breastbone lay.   _ Fuck _ !  His traterous cock twitched automatically at the sensation and he shoved at Cat-Sam’s chest.  It was like pushing against a brick wall. Cat-Sam squinted his eyes at him, not stopping his feet or his purring.  Dean shifted his hips the best he could with the weight on top of him and got the pressure off his dick enough not to be affected.

 

He couldn’t help but think about how fucked up their lives were sometimes.

 

~*~

 

Dean woke to the familiar purr of a huge cat and an equally familiar weight on his lower half.  The purring was stimulating again and he wasn’t full awake enough to care one way or the other. He smacked his lips and shifted his hips slightly, rubbing his morning wood over the warmth that blanketed him on his bed.

 

The purring increased in intensity and Dean grunted slightly.  Then he felt fingers grip at his sides, much the same way Cat-Sam had flexed his claws and his eyes shot open.  He looked down to see a mop of brown hair on his stomach. Sam’s broad shoulders beyond that and his long tanned arms attached to hands that had fingers that were massaging into his sides.

 

“Holy fuck!” Dean yelled bucking his hips up.  This startled Sam awake who jerked up and looked at him with sleepy eyes.  Sam looked down at his hands on either side of Dean’s hips and then back up at his brother’s face.  He scrambled out of the bed, tripping over the lose sheets and falling off the side on his back.

 

Dean scrambled back against the headboard, knocking the laptop off the other side of the bed in the process.  Sam was up off the floor in a shot, standing in Dean’s room staring at him. Naked. Dean’s eyes traveled down Sam’s defined body to his half hard cock and they widened then shot back up to his face.  But Sam wasn’t looking at Dean’s face, he was looking at Dean’s own wood.

 

Sam’s eyes shot up to Dean’s and realized he’d been caught.  They widened and he reached down to hide his own nakedness. If only his hands were big enough.  Dean pulled his knees to his chest and buried his face in his hands.

 

“Why don’t you go get dressed, Sam.  I’ll meet you in the kitchen.” His words were muffled by his hands but Sam heard him clear as day.  Sam perked a bit and cocked his head. He heard a lot of things, actually. He nodded and made his way to his own room, stopping and examining the holes in Dean’s door.

 

Sam made his way to his room as he recounted what had happened last night.  Vividly. He remembered everything. The shifting hadn't hurt. Like, at all.  And he'd never really contemplated it before but it kinda surprised him. He was completely himself, but also a cat.  Or something.

 

He remembered picking up his brother’s scent and being able to decipher different notes in it.  His cat brain picked it apart and could tell the omega was about a week from his heat. Huh. Sam paused inside his bedroom door and wondered what that was about for a second.  He shook his head and dressed himself.

 

While human, Alpha Sam had no issues with holding his attraction to his omega brother at bay his cat brain held no such qualms.  The cat he had shifted into last night had been full on trying to woo the omega. Halfway to the kitchen he stopped in the hallway, another thought occurring to him.  He'd been subconsciously doing it all week. Like when he'd brought Dean his record.

 

He entered the empty kitchen and started the coffee maker as he continued to contemplate his cat form’s behavior.  His thoughts were a bit scattered and random, he was having a hard time focusing on one thing. Like, how he was more concerned about how he was going to explain this to Dean than he was about the fact he had been a giant cat last night.

 

When the coffee was finished Sam made his mug and sat at the table waiting for Dean.  His eyebrows slightly furrowed as he was lost in thought. The Alpha had been wanting to claim the omega for a while now.  He just didn't think Dean felt the same. And instead of make things awkward he just kept it to himself. It wasn't too hard, he was satisfied just being around.

 

Except now Sam's senses seemed to have peaked.  All of them. He could smell Dean everywhere. It was sweeter, almost a floral note to it.  When he licked his lips he could taste it faintly, along with salt and what had to be  _ Dean _ .  He could hear the coffee dripping into the pot like it was right in front of him and not across the kitchen.

 

Then there was the footfalls of boots he'd know anywhere.  They were pretty far off down the hall, but he heard them. Soon he could smell the sweet omega scent down the hall.  Before today he might not have even scented Dean across the room. If this was his new normal state he was going to be in trouble

 

He didn’t look up as Dean entered the kitchen.  He did notice the small falter in his step when he saw Sam sitting at the table hunched over his coffee.  Dean took in a breath as if to say something, gulped, and moved to the counter instead to get his own mug.

 

After Dean sat down across from Sam they stayed silent for a moment, neither looking up.  Both just trying to figure out what to say. Leave it to the older Winchester to break the ice.

 

“So, uh.  You’re a werecat.  Or something. Huh.”  Sam’s eyebrows shot up as he looked at his brother through his lashes.  Dean was, likewise, looking sheepishly at Sam. His inner Alpha (un)helpfully supplied  _ submissive _ .

 

“Yeah.  Guess I didn’t get off so easily after that bite.  Did I hurt you?” Sam knew that he didn’t. At least not mentally or emotionally.  He did remember everything, after all. He remembered being cognizant, making choices.  However, those choices were driven by a new feline instinct instead of Sam’s human brain.  His werecat Alpha was more wild and less concerned with society's ideas of propriety.

 

“How much do you remember?” Dean asked, clearly hedging around answering Sam.  The Alpha scratched his head a bit, trying to look like he was thinking back. He was really wondering how much he should tell the omega.  Would his brother be worried for his own safety if Sam told him his werecat Alpha wanted to make him mate?

 

“Uh, you know.”  Sam paused, holding up his hands.  Dean looked at him with expectant eyes, practically pleading with a look for Sam to tell him everything was going to be fine.  Sam sighed, resigned, and put his palms on the table. “I remember everything, Dean. All of it.” Dean let out his own sigh and sat back in his chair, eyeing the Alpha across from him curiously.

 

“Well, were you awake?  Like, I know you said you remember it all, but could you control the cat?”  Sam closed his eyes and took a deep breath. He had to tell him.

 

“Uh, yeah, Dean.  I was in there. It wasn’t like the cat was another being, I was him.  He was me. We shared the same Alpha instinct and- I don’t know, it’s kinda hard to explain.”  Sam paused then, his face scrunching slightly as he tried to find the words to describe what it felt like.  Dean waited patiently, anxiously, for Sam to continue. He didn’t want to speak and throw off his Alpha’s train of thought.

 

“It was almost like, I was more raw.  Less, uh, less inhibitions? I guess. Like my instincts were right there under the surface and there wasn’t anything there to fight them.  It was all me, just none of the barriers that make people over think what they feel. Does that make sense?” The pleading questioning on Sam’s face had a lump forming in Dean’s throat.

 

“Uh, yeah, Sammy.  I guess. So, when Cat-you grabbed me-”  Dean’s voice shuddered and he dropped his forehead to his hand, trying to gain the confidence to say what he wanted.  He was nervous and he didn’t even know what answer he wanted. “You bit me, Sam. Right on the back of my neck. It felt…  It felt like, uh, like,” Dean cut himself off with a growl and stood from the table, pacing the kitchen a few times. Sam sat quietly, clutching his mug.

 

“Can you shift again?  Or was it because of the full moon last night?”  Sam turned slightly in his chair to look at Dean out of the corner of his eye.  He shrugged the shoulder he was looking over.

 

“I’m not sure.  I haven’t tried yet.”

 

“Do you want to?”  Sam froze in his chair.  He ran the words threw his head a few times before turning slowly to look at the omega.  Dean was standing in the middle of the kitchen, his shoulders hunched in slightly, his head tilted down.   _ Submissive _ , his cat-brain supplied again.

 

“Dean, do you want me to shift again?” Sam’s voice was low, almost a growl as he white-knuckled the table and the chair.  He didn’t miss the small shudder that went through his brother’s body. “ _ Dean _ .”

 

The omega’s head snapped up at Sam’s commanding tone, Sam’s skin tingled as if the shift was already coming.  His brother shrugged helplessly and looked at Sam with pleading eyes. The Alpha could only imagine the war going on in his brother’s head.  But there was no mistaking the tang of omega arousal faintly permeating the air.

 

“You said you could control it right?  That it was all you? You won’t hurt me, Sam.  I know it.” Sam stood, slowly, stalking across the kitchen until he was right in front of his brother.

 

“What are you thinking about, Dean?”  He was so close now the omega could scent him clearly.  Sam’s scent had changed along with his body. He had noticed the difference over the past week or so, since the bite.  But now it was stronger, sharper, more  _ Alpha _ .  It was doing things to him he’d never considered before.  Just thinking about how Sam had bit his neck had him throbbing.  Just then Sam let out another growl.

 

“Uh, I just.  I know you won’t hurt me.  I mean, not more than I want you to-” Dean’s words were cut off and his breath rushed from his lungs in a huff as he was spun and shoved, chest first, into the wall.  A solid, heavy weight on his back held him there and he was engulfed in Sam’s Alpha pheromones. Dean whined and didn’t bother trying to fight him off.

 

“What are you saying, Dean?”  The omega panted against the cooled surface of the wall and squeezed his eyes shut.  He didn’t know! He had no idea what was going on, his body seemed to be on autopilot and Sam was the catalyst.

 

Then he felt something soft creeping up the pant leg of his jeans.  Sam leaned in and ran his cold wet nose up the line of Dean’s neck, causing him to twitch and pull away at the tickle of thick hairs that followed.  Sam chuckled darkly when Dean’s head tilted to the side, giving him more room. A course, wet tongue ran up his neck and Dean’s eyes rolled back when he recognized it as Cat-Sam.

 

The soft thing in his jeans wrapped around an ankle and the tip flicked a couple times across his shin.  It was a fucking tail. Sam had at least a partial shift going on and suddenly Dean started pushing slightly, questioningly, against the wall.  He wanted to see.

 

The Alpha growled at him and snagged Dean’s shoulder in slightly pointier teeth.  Dean groaned at that, squeezing his eyes shut in embarrassment. Sam let him go and ran his cat tongue over the indents.

 

“Be still, omega.”  The tone in Cat-Sam’s voice brokered for no argument and Dean stopped trying to move from where he stood.

 

“What’s going on, Sam?”  He hated how whiny he sounded.  But it was almost like what Sam had described.  He was himself, just running on instinct. His omega instinct, it looked like.  And that omega was looking for an Alpha. Instead of answering Sam thrust forward and rubbed his cock over the omega’s denim clad ass.  He chuckled when Dean pushed back.

 

Just as sudden as he found himself face-first against the wall Dean was spun again and got his first good look at semi-Cat-Sam.  (He wasn’t going to call him that). Cat-Sam had a shorter nose, cat-shaped and wet. The pupils in his eyes were small lines, and his ears were slightly pointed and a little more furry with tufts on the ends.  There was a tail peeking off to the side and when Sam licked his lips Dean saw the pad of his tongue and his slightly sharper teeth.

 

“Holy shit,” the omega exhales softly.  Sam just grinned and leaned in to scent Dean’s pulsepoint, that he could see jumping under his skin.  Sam’s hands clutched at Dean’s hips, his fingernails pinching slightly as they were pressed through his shirt.

 

“What do you want, omega?”  Dean’s breath hitched at the confidence and roughness of Sam’s voice.

 

“You,” he choked out in response.  It was a battle to keep his hands at his sides, but Sam hadn’t said he could move or touch and when the  _ fuck  _ did that matter?  Sam leaned back and raised an eyebrow at Dean, expecting a bit more.  Dean’s breath picked up and he could feel his ears burning with embarrassment.

 

“Alpha.  I want you, Alpha.”  Sam surged forward and caught Dean’s lips between his, his mouth open before contact was even made.  One hand shoved Dean’s shirt up his chest, the other pulling him from the wall to remove the clothing all together.  Dean’s head spun with the initial contact, too shocked at the situation to react on his own.

 

He was kissing Sam.  Did he want to kiss Sam?  His omega did. Or at least wanted an Alpha.  And it was really responding to the prowess of the Alpha in front of him.  It suddenly didn’t matter that it was his brother. It was strong, and powerful.  Commanding with just it’s presence. The Alphaiest Alpha to ever Alpha.

 

His pants falling around his ankles shocked him out of his musings and he realized, as he stepped out of his jeans, he was naked in the kitchen while Sam was fully clothed.  Sam grabbed the back of his neck and growled in their kiss before pulling away and shoving Dean to his hands and knees on the floor. Before he could begin to convince himself to get up Sam was on his knees behind him, spreading his cheeks and diving in with that textured tongue.

 

“Holy fuck!” Dean yelled as he fell to his chest on the floor.  His hole clenched at the sudden stimulation, so different than any other rim job he’d ever gotten.  He was probably in love with Sam’s cat-tongue already. The Alpha chuckled against his pucker, causing more sensation to the nerve endings before wiping over it a few more times.

 

He would back up and watch Dean’s asshole flutter, opening slightly more after each turn.  Sam licked over it a few more times before he watched Dean fully relax with a groan. Maybe, in his half-cat state, if he weren’t copulating he would have had the frame of mind to remove his shirt without destroying it.  But the cat’s Alpha wanted to mate  _ now _ .

 

Sam ripped the shirt from his torso and tore away the button on his jeans.  The zipper was ripped apart as he pulled them down his thighs, just under his balls.  Dean looked over his shoulder as Sam gripped his hips and saw Sam’s chest and stomach was still ripped, just now with a soft dusting of fur.  And why was  _ that  _ hot?

 

“This is all new, I’ll try not to hurt you,” Sam said before nudging Dean’s hole with the tip of his uncut cock.  Dean groaned and dropped his head onto his forearms, spreading his knees a bit wider and arching his back. Sam felt the small hairs on his back rise to stand at the sight of his omega’s full submission.  He thrust his hips a bit, putting more pressure on Dean’s slick hole.

 

Sam’s saliva would work for now, but as soon as he got inside and pumping Dean’s channel would slick itself.  He just had to be patient and not move too fast. A little more pressure and the head popped in. His foreskin was pushed back as he entered the tight space.

 

Dean raised his head and keened at Sam’s slow entry, trying to push back and make his Alpha go faster.  Sam growled and leaned over his back, biting the nape of his neck again and stilling him with a whine. Once the omega settled Sam started thrusting slow and shallow once more.  Each shift of his hips rubbed his soft furred chest rubbing over Dean’s back.

 

When he was finally fully seated he let out a high growl in his throat and released Dean’s neck from his grip.  His brother shook his head a bit and shot a glare over his shoulder, but Sam just smirked and ground his hips against his ass a bit harder.

 

As Sam pulled out a bit his cock was slicked by the glands just inside Dean’s rim.  He pushed back in and pulled back out, dragging more slick out with him. Soon Dean’s channel was appropriately lubricated and Sam started thrusting a bit harder.  He had the omega moaning under him in no time.

 

Before long the slap of skin on skin echoed in the kitchen, Dean’s moans causing a growl of triumph out of Sam every time he exhaled.  He looked down to see his fingers digging into his brother’s sides, just not enough to tear skin. He watched his knot start to bulb at the bottom, a little surprised he still had it, but it must be his half human in this state.  He still wondered about his cat side.

 

Dean started thrusting back into him on each in stroke, the pressure nailing his prostate and causing him to tighten slightly as he prepared for orgasm.  Sam leaned forward again and took Dean in his mouth, right where his shoulder and neck met. He felt his knot slip in and out of Dean’s channel a couple times before Dean jerked and howled in surprise.

 

Sam kept a tight grip on the omega under him as he thrashed slightly, trying to dislodge the cock in his ass.  Then the knot stuck, and Dean stilled as the pressure of the bulb stimulated his prostate and he came untouched and yelling his brother’s name.  Sam came right after to the pulsing constriction of Dean’s channel. He bit down on Dean’s shoulder, easily sliding his teeth into flesh and drawing blood.  Dean screamed again and jerked underneath him, but Sam had a firm hold everywhere.

 

The fell to their sides, curled up on the kitchen floor.  Sam released his brother’s shoulder and licked over the wound with his cat tongue, causing Dean to twitch every now and then.

 

“Dude, what the fuck was that?” Dean asked still slightly breathless.

 

“Claimed you,” Sam said between licks, “mine now.”  Dean chuckled but shook his head.

 

“Yeah, I got that much.  We’ll discuss that later.  Just before your, uh, knot.  Felt like you were trying to turn me inside out from my ass.”  Sam paused with his tongue over the wound made a curious sound.

 

“Sam?”  The Alpha cleared his throat.

 

“Uh, yeah.  I’m half shifted, I guess.  Maybe the moon? But anyway, I must have a cat dick, too.”  He snuggled his face in between Dean’s shoulder blades, half to hide, half to scent his mate.

 

“A cat-  What the fuck, Sam!”

 

“I don’t know!  This is all new, man.  I haven’t explored any of it.”  Dean huffed a sigh and dropped his head to the tile floor.  Sam tired not to but he couldn’t help but chuckle slightly.

 

“Shut the fuck up, it’s not funny.”  Dean tried to sound angry.

 

“Don’t talk to your Alpha like that!” Sam scolded, he wasn’t made but he used his Alpha tone anyway.  Dean’s body jerked slightly making him whimper. Sam laughed into his back again.

 

“Bitch.”

 

“Jerk.”

 

The floor was a bit uncomfortable but they both fell asleep to the pattern of Sam’s breathing, Dean would never admit the purr that suddenly accompanied it was soothing in the least.

**Author's Note:**

> Full Prompt:  
> On a routine hunt gone wrong, Sam gets bitten / gets some kind of serum injected that turns him into a werecat. He develops all sorts of catlike tendencies and full on transforms into a giant cat on the next full moon. He's not rabid during that time, but not harmless and friendly either. Now he and Dean have to find a cure and also deal with the feelings Sam just can't hide anymore, because of his stronger instincts.  
> Examples of possible cat traits:  
> \- purring  
> \- kneading  
> \- rubbing against objects  
> \- headbutting Dean  
> \- licking himself clean, licking Dean  
> \- depositing prey on the doorstep   
> \- napping on sunny spots  
> \- aversion to salad  
> \- scratching  
> \- hackles (hair) rising at threats  
> \- good sense of smell  
> And anything and everything else you can think of.  
> Also, it would be great if they didn't know what's wrong at first.


End file.
